A New Chemical Inhibitor to Mitigate Swelling of Sodium and Calcium Bentonite during Drilling Process

Abstract

Clay swelling during drilling operations is one of the challenges faced in the oil industry. While both oil-based and syntheticbased muds have been successful at reducing clay swelling, the environmental concerns of oil-based muds and the high cost of synthetic-based muds limit their usage. Commercial water-based inhibitors like sodium chloride (NaCl), potassium chloride (KCl), cesium formate (CHCsO2), ammonium chloride (NH4Cl), and tetramethylammonium chloride (C4H12NCl-) are commonly used. However, some inhibitors have limitations, such as the toxicity of KCl, which according to the Environmental Protection Agency, cannot be used at concentrations higher than 5%. Other limitations include their impact on the rheology of drilling mud, cost (CHCsO2, C4H12NCl-), and their limited behaviour at high temperatures and pressures (NaCl). In this study, novel clay inhibitors for water-based drilling muds were characterized. A capillary suction timer (CST), a filtration time test, energy dispersive spectroscopy (EDS), and a scanning electron microscope (SEM) were used for the experiments. Testing was conducted on Na and Ca bentonite mixed with water-based drilling mud (WBDM) and commercial inhibitors, as well as novel inhibitors at 3%, 4%, and 5% concentrations.